Multi-office telephone-exchange system.



E. H. CLARK.

MULTI-OFFICE TELEPHONE EXCHANGE SYSTEM.

APPLlcATxoN FILED APR.9.1917.

1,292,257. Patented Jan. 21,1919.

4 SHEE-SMSHEE l.

v ull/ll by V n.. mn: mnu ou.. run-muuu. nummern. n n

E. H. CLARK.

MULTI-OFFICE TELEPHONE EXCHANGE SYSTEM.

APPLICATION FILED APR. 9.1917- Patented Jun. 21, 1919.

4 SHEETSHSHEET 2.

IEM.

IIHII v ly.

.wunmcvom a c E. H. CLARK.

MULT10FF|CE TELEPHONE EXCHANGE SYSTEM.

APPLICATION FILED APR. 9, I9I7. 1,292,257. Patented Jan. 21,1919.

I Iy. WM M 5 n.. mus mnu m. rnmunm. 'mum-ml. n c.

Patented Jan. 21,'1919.

4 SHEETS-SHEET 4.

E. H. CLARK.

MULTI-OFFICE TELEPHONE EXCHANGE SYSTEM.

APPLICATION man APR. 9, 1911.

www AMH uww .w ...,MSN MH im@ ...Eq ...5...

Q @wi L ma annu nnss: rnmuumu. 'Ammann'. A c

UNITE@ 'STATES PATENT OFFICE.

EDGAR I-I. CLARKJ OF NEW YORK, N. Y., ASSIGNOR TO WESTERN ELECTRIC COMPANY, INCORPORATED, OF NEW YORK, N. Y., A CORPORATION 0F NEW YORK.

MULTI-OFFICE TELEPHONE-EXCIIAN GE SYSTEM.

Specification of Letters Patent.

Patented J an. 21, 1919.

Application led April 9, 1917. Serial No. 160,690.

To all whom t may concern.'

Be it known that I, EDGAR H. CLARK, a citizen of the United States, residing at New York, in the county of New York and State of New York, have invented certain new and useful Improvements in Multi-Oftice Telephone-Exchange Systems, of which the following is a full, clear, concise, and exact description.

This invention relates to telephone eX- change' systems, and more particularly to multi-oiiice systems in which a call is eX- tended to a final connecting operator over a trunk line.

It is the object of this invention to provide an improved means for informing a final 'connecting operator of the number of the wanted line by means of an automatically operated indicating device.

A feature of the invention is the use of a combination of relays to control the indicating lamps, the arrangement being such that the same set of relays and lamps may be used successively to indicate the various digitsk constituting the number of the desired line.

The'invention has been shown applied to a telephone exchange system of the wellknown power driven semi-automatic type, but is obviously capable of arrangement for use in other systems.

It is thought that the invention will best be understood fromthe following detailed description, reference being had to the accompanying drawings.

In the drawings, Figure 1 shows the substation set of a calling subscriber and the operating circuits of an automatic switch by means of which a call may be extended to a final connecting operators position. Fig. 2 shows a combination of relays to control the lighting of indicating lamps to inform the final connecting operator of the number of the called line. Fig. 3 shows diagrammatically a cord finder switch and operating circuits therefor, an impulse sending switch being indicated in the lower right-hand corner of Fig. 3 within the dotted lines. Fig.

"4 shows diagrammatically an operators key set, and register switches controlled thereby.

Fig. 5 shows the character of the impulses necessary to operate the relay combination to cause lighting of any desired lamp.

The subscriber at station 11 may initiate a call by removing his receiver from the switchhook, whereupon line relay 12 will be energized to cause the display of lamp signal 13 in the well-known manner. An operator, one of whose cord circuits is indicated at O, upon observing the lighting of lamp 13 inserts an answering plug 14 into a jack 15 associated with the lamp 13, whereupon a circuit is completed from grounded battery, winding of cut-off relay 16, sleeve contacts of jack 15 and plug 14, winding of relay 17 to ground. Relays 16 and 17 are energized in this circuit, relay 16 attracting its armatures to remove the control of the line relay 12 from the calling subscriber in the wellknown manner.

Relay 17 upon energization completes a circuit from grounded battery, power magnet of sequence switch 100, contact 102, armature and front contact of relay 17 to ground, for moving this sequence switch out of position 1 and into position 2 under the control of its master contact 101.

When sequence switch 100 arrives in position 2, a circuit is completed from grounded battery, power magnet of sequence switch 200, contact 202, conductor 18, contact 103, to ground, for moving sequence switch 200 out of position 1 and into position 2 under the control of its mastei1 contact 201.

In position 2 of sequence switch 200 a circuit is completed from grounded battery, winding of up-drive magnet 19, contact 203, left-hand armature and back Contact of relay 20, to ground. The energization of magnet 19 causes the brush shaft 21 of a cord finder to be elevated in Search of the connecting circuit which the operator has taken for use. When test brush 22 of the cord finder engages terminal 23 associated with such connecting circuit, a circuit is completed from grounded battery, winding of relay 20, contact 204, brush 22, terminal 23, conductorl 24, contact 104, to ground. Relay 20 is energized in this circuit, and breaks at its lefthand armature the energizing circuit of updrive magnet 19, which denergizes and brings the iinder brush set to rest on the terminals of the desired cord. Relay 20 upon energization completes a locking circuit for itself from grounded battery, winding` of relay 20, Contact 205, right-hand armature and front contact of relay 20, brush 25, terminalv 26, conductor 27, contact 105, to ground. A circuit is completed at the same time from grounded battery, power magnet of sequence switch 200, contact 206, left-hand armature and front contact of relay 20 to ground, for moving this sequence switch out of position 2 and into position 3.

After the operator has inserted plug 14 into jack 15, she depresses listening key 28, thereby connecting her head-set with the calling substation. She may then converse with the calling party, and learn the number of the desired line.

If we assume that the number of the called line is 9876-1717, and that it may be reached through an ofiice, the trunks to which may be selected by the action of the selector switch shown in Fig. 1 upon the depression of district key No. 2, she will thendepress keys of the key-set shown in Fig. 4, as follows: district key No. 2, thousands key No. 9, hundreds key No. 8, tens key ilo. 7, units key No. G, and stations key W. rEhe registers 300, 400, 500, 600, 700 and 800 have no normal positions, and are started in rotation as soon as sequence switch- 200 arrives in position 2, their circuits extending from grounded battery, through their respective power magnets, the left-hand armatures and back contacts of their associated controlling relays 29, 30, 31, 32, 33 and 34, to conductor 35 in multiple, and thence to ground through contact 207. Then register 300 arrives in position 2, a circuit is completed from grounded battery, winding of relay 29, contact 301, depressed key No. 2, to ground. Relay 29 in energizing opens at its righthand armature the driving circuit of register 300, and this register is brought to rest in position 2. 'Similarly relay 30 operates to bring register 400 torest in position 9; relay 31 to bring register 500 to rest in position 6; relay 32 to bring register 600 to rest in position 7 relay 33 to bring register 700 to rest in position 6; and relay 34 to bring register 800 to rest in position 4. When the stations register 800 is in position 0, stations lamp O will be lighted, indicating that the line is not a party line. In position 1 of register 800 lamp J will be lighted, in position 2, lamp M, in position 3, lamp R, and in position 4, lamp I/V. In position 5 of the stations register, lamp I will be lighted to indicate that the number sent is not a party lineand that its number is greater than ten thousand; that is, the lighting of lamp` I would correspond to the ten thousands digit 1 in a line whose 'number is greater than ten thousand. W'hen all the controlling relays have been energized, thereby indicating that all the registers have been set, a circuit is completed from grounded battery, power magnet of sequence switch 200, contact 208, conductor 36, through the left-hand armatures and front contacts of such control relays 29, 30, 31, 32, 33 and 34, to ground, for moving this sequence switch out of position 3 and into position 6.

"While sequence switch 200 is passing through positions 4 and 5, circuits are completed for th-e-key-release magnets 37, 38, 39, 40, 41 and 42, from grounded battery, the windings of these relays, to conductor 43 in multiple, and thence to ground byway of contact 209. The operation of these magnets allows the depressed keys of the keyset to return to their normal positions.

wWith sequence switch 100 in position 2 and sequence switch 200 in position 6, a fundamental circuit is established from grounded battery, winding of relay 44, contact 106, conductor 45, terminal 46, brush 47, contact 210, winding of stepping relay 48, outer armature and back contact of the No. 0, counting relay, brush 49, terminal 50, conductor 51, contact 107, to ground. Relays 44 and 48 are energized in this circuit, relay 44 completing a circuit from grounded battery, power magnet of sequence switch 100, contact 108, left-hand armature and front contact of relay 44, to ground, for moving this sequence switch out of position 2 and into position 3, and at its right-hand armature completing a locking circuit for itself through contact 109 to ground, over the path described.

In position 3 of sequence switch 100 a circuit is completed from grounded battery, winding of up-drive magnet 55, contact 111, left-hand armature and front contact of relay 44, to ground.. The magnet 55 upon energization forces a driving ribbon 5G' into engagement with a roller constantly rotating in the direction indica-ted by the arrow to cause the elevation .of a brush carrying rod 57. The brush rod 57, in moving upward, carries a brush set 58 over the terminals of trunk lines arranged in groups, and at the same time causes a commutator brush 53to be advanced over a commutator plate 54. In order to simplify the description, it has been assumed that only one brush set is carried by the rod 57.

Relay 48, when energized, completes a circuit from grounded battery, Winding of the No. 2 counting relay, armature and back contact of the No. 2 counting relay, district register contact 302, conductor 52, contact 211, armature and front contact of relay 48, to ground. Counting relay No. 2 is energized and prepares a circuit for counting relay No. 2 in the well-known manner. When commutator brush 53 engages the first conducting segment of commutator 54, a circuit in shunt of the fundamental circuit is vcompleted from grounded battery, winding of relay 44, right-hand .armature and front contact of relay 44, contacts 109, 110, commutator 54, brush 53, to ground. Relay 48 is shunted by this circuit and denergizes, permitting the No. 2 counting relay to energize by way of contact 212 in the well-known manner. Upon the third shunting of the stepping relay 48, at which time brush set 58 will be below the No. 2 group of terminals, the No. 0 counting relay is energized, opening at its outer armature the lower branch of the fundamental circuit, and when, a moment later, brush 53 engages an insulating portion of commutator 54, relay 44 is denergized, opening at its lefthand armature the circuitiof up-drive magnet 55, and bringing the brush set 58 to rest just below the lirst terminal in the desired group. The No. 0 counting relay upon energization completed a circuit from grounded battery, power magnet of sequence switch 200, contact 213, inner armature and front contact of the 0 counting relay, to ground, for moving this sequence switch out of position 6 and into position 7. Upon leaving position 6 the locking circuits of the counting relays are broken, and thes relays are restored.

The denergization of relay 44 resulted in the establishment of a circuit from grounded battery, power magnet of sequence switch 100, contact 112, left-hand armature and back contact of relay 44, to ground, for moving this sequence switch out of position 3 and into position 6. A circuit is then established from grounded battery, lower winding of test relay 59, contact 113, to ground. Relay 59 is energized and completes-a circuit from grounded battery, power magnet of sequence switch 100, contact 114, lowerv armature and front contact of relay 59, to ground, for moving this sequence switch out of position 6 and into position 7.

In position 7 of sequence switch 100 a circuit is established from grounded battery, winding of up-drive magnet 55, contact 115, lower armature and front contact of relay 59, to cause the brush set 58 to be advanced in search of an idle trunk in the selected group. If we assume that the test terminals 60, associated with busy trunks are designated by ground potential, and that the test terminals oi idle trunks are characterized by theabsence of potential, relay 59 will be maintained energized while test brush 61 is engaging terminals 60 associated with busy trunks, this holding circuit extending from grounded battery, upper winding of relay 59, upper armature and front contact of relay 59, test brush 61, test terminal 60, to ground. As soon as the test terminal of an idle trunk is encountered, this circuit will be broken and relay 59 is denergized, breaking at its lower armature, the circuit of updrive magnet 55, which denergizes and brings the brush set to rest on the terminals of an idle trunk leading to a desired office. Ground potential is supplied to test brush 61 from ground, contact 116, upper armature and back contact of relay 59, to test brush 61, to render the test multiples of this trunk busy to other testing selectors. Relay 59 upon denergization also completes a circuit from grounded battery, power magnet of sequence switch 100, contact 117 lower armature and back contact of relay 59 to ground, for moving this sequence switch out of position 7 and into position 11.l

Then sequence switch 200 arrived in position 7, a circuit was completed from grounded battery, power magnet of impulse sending sequence switch 900, contact 902,

' contact 215, to ground, for moving this sequence switch out of position 1 and into position 2, under the control of its master contact 901. As soon as the brush set 58 is positioned on the terminals of an idle trunk, a circuit is completed from grounded loattery, winding of relay 62, lower left-hand winding of a repeating coil 63, contact 64 of a key K associated with a final connecting operators position, one of whose cords is indicated at O, trunk conductor G5, terminal 66, brush 67, contact 118, conductor 51, terminal 50, brush 49, contact 903, winding of relay 68, to ground. Relays 62 and 68 are energized in this circuit. The energization of relay 68 completes a circuit from grounded battery, power magnet of sequence switch 900, contact 904, armature and front contact of relay 68, to ground, for moving this sequence switch out of position 2 and into position 3.

The energization of relay 62 completes a circuit for lamp G9 from grounded battery, lamp G9, conductor 70, armature and front contact of relay G2, lower armature and back contact of relay 71, resistance 72, to ground. The lighting of lamp 69 informs the operator at O that a call is coming in over the trunk line associated with such lamp G9. She thereupon depresses key K, causing thereby the interruption of the circuit of relay 08. which denergizes and completes a circuit from grounded battery, power magnet of sequence switch 900, contact 905, armature and back contact of relay 68, to ground. for moving this sequence switch out of position 3. The sequence switch 900 then rotates through its remaining positions without stopping and in so doing sends out sets oi' impulses as will. be described, and then returns to its normal position, which is posi.- tion 1.

Vhen sequence switch 900 arrives in position 4. a circuit is completed from grounded battery, magnet of sequence switch 200, contacts 214 and 906, to ground, for moving this sequence switch out of position 7 and into position 8.

The impulses to light the stations indicating lamp are sent first, after which impulses to light the thousands, hundreds, tens and units lamps will be sent in the order named. The operation ot' the relay combination shown in F ig. 2, with the stations register set in position 4, is as lfollows.

lNhen sequence switch 900 arrives in position 4 and until it leaves position 6, an impulse will be sent over the lower trunk conductor from negative pole of battery, contact 907, conductor 74, contact 802, conductor 75, contact 908, brush 49, terminal 50, conductor 51, contact 118, brush 67, terminal 66, conductor 65, contact 76 of key K, winding of relay 77, to ground. Relay 77 isenergized in this circuit, causing in turn the encrgization of relay 78, the circuit of this relay extending from grounded battery, the right-hand winding of relay 78, left-hand armature and front contact of relay 77 to ground. Relay 78 is energized .and locks itself toground at the armature and back contact of slow-release relay 7 9, this locking circuit extending from grounded battery, through the right and left-hand windings of relay 7 8, the inner left-hand armature and front contact thereof, conductor 80, armature and back contact of relay 79, to ground. When sequence switch 900 arrives in position 4-1/4 and until it leaves posit-ion 6, current will be sent over the upper trunk conductor 73 from positive pole of battery, contact 909, conductor 81, contact 803, conductor 82, Contact 910, contact 216, brush 47, terminal 46, conductor 45, contact 119, brush 83, terminal 84, trunk conductor 7 8, contact 85 of key K, winding of polarized relay 86, winding of relay 87, to ground. Relays 86 and 87 are energized in this circuit and remain energized until sequence switchA 900 leaves position 6. Relay 86 is polarized and is responsive only to impulses from positive battery.

Upon the energization of relays 86 and 87, a circuit is completed from grounded battery, winding of relay 79, lamp W, outerinostarmature and back contact of relay 88, outermost left-hand armature and back contact of relay 89, outermost armature and front contact of relay 7 8, armature and front contact of relay 86, right-hand armature and front contact of relay 87, to ground. In this circuit, lamp 7 is lighted, indicating that station W of the desired party line is the station to 1be signaled. Relay 79 is also energized in this circuit.

When the sequence switch 900 leaves position 6, relays 86, 87 and 77 are denergized, the denergization of relay 87 causing in turn the denergization of relay 79 and the extinguishing of lamp W. When relay 79 was energized and attracted itsL armature, the locking circuit of' relay 78 was broken. When relay 79 was energized, a circuit was completed from grounded battery, resistance 90, conductor 91, upper winding of relay 88, upper winding of relay 92, armature and front contact of relay 79 to ground. Relays 88 and 92 are not energized at this time, since they are shunted by a path to'ground at the right-hand armature and front contact of relay 87 When relay 87 is'denergized this shunt is removed and relays 88 and 92 are energized and attract their armatures and then maintain them` attracted throughout the remainder of the signaling operation, since holding circuits are established from grounded battery, through the lower windings of relays 88 andv 92, conductor 93, contact 94 of key K, to ground. The circuits through the lower windings of relays 88 and 92 were in existence as soon as the key K was operated by these relays, but are so designed that Vthe energizingv force of their lower windings is not suflic'ient to cause them to attract their armatures, but is effective to maintain their armatures in an attracted position after having been actuated upon the energization of the upper operating windings oi" these relays.

When sequence' switch 900' arrives in position 6-5/8, an impulse will be sent over the lower trunk conductor 65 from grounded battery, contact 911, conductor 95, contact 403, conduct-or 75, and thence over the path described, through the windings of relay 77 tov ground. Relay 77 is energized and causes the energization of relay 78 over a circuit from grounded battery, winding of relay 78, left-hand armature and front contact 0f relay 77 t0 ground. Relay 78 locks up to ground at the armature and back contact of relay 79 as before. When sequence switch 900 leaves position 6-5/8, the energizing cir! cuit of relay 77 is broken and this relay is deenergized, causing the energization of relay 89 over a circuit from grounded battery, right-hand operating winding of relay 89, inner right-hand armature and front contact of relayv 7 8, right-hand armature and back contact of relay 77 to ground. Relay 89 locks up through its right and left-hand windings in series and its inner left-hand armature and front contact to ground at the armature and back contact of relay 79. When sequence switch 900 reaches position 7 -1/8, another impulse will be sent, by way of Contact 911 over the path described, to energize relay 77. Upon the energization of relay 77, a circuit is completed from grounded battery, right-hand winding of relay 96, inner right-hand armature and front contact of relay 89, left-hand armature and front contact of relay 7 7 to ground. Relay 96 is energized and locks up through its inner letthand armature and front contact to ground at the back contact and armature of relay 79. When sequence switch 900 leaves position 7-1/8, relay 77 is denergized and causes the energization of relay 97 over a path from grounded battery, right-hand operating winding of relay 97, inner right-hand armature and front contact of relay 96, righthand armature and back contact of relay 7 7, to ground. Relay 97 locks up through its right and left-hand windings in series, and its inner left-hand armature and front con tact, to ground at the armature and back contact of relay 79.

When sequence switch 900 arrives in position 7-3/4 and until it leaves position 9, negative current will be supplied to the upper trunk conductor over a path from negative pole of battery, contact 912, conductor 98, contact 404, conductor 82, and thence to ground through the windings of relays 86 and 87 over a path previously described. Since this impulse is from the negative pole of battery, relay 86 will not be energized. Relay 87 is, however, energized, and, upon its energization, a circuit is completed from grounded battery, winding of relay 79, lamp 9, right-hand armature and front contact of relay 97, outer right-hand armature and front contact of relay 96, outer right-hand armature and front contact of relay 89, outer right-hand armature and front contact o't relay 78, armature and back contact of relay 86, right-hand armature and front contact of relay 87, to ground. Lamp 9 is lighted in this circuit, indicating that the thousands digit of the desired line is 9. Relay 7 9 is also energized in this circuit and opens one branch of the locking circuit of selecting relays 7 8, 89, 96 and 97 and when sequence switch 900 leaves position 9, relay 87 is denergized and allows these relays to restore, thus placing the relay combination in condition for reoperation.

When sequence switch 900 arrives in position 9-5/8, an impulse will be sent over the lower trunk conductor 65 from grounded battery, contact 913, conductor 805, contact 503, conductor 75, and thence to ground through the winding of relay 77, over the path previously described. Relay 77 upon energization, completes a circuit at itslefthand armature and front contact to cause the energization of relay 78, as previously described. Relay 78 upon energization, locks up to ground at the armature and back contact of relay 79, as described. When sequence switch 900 leaves position 9-5/8, relay 77 is denergized, completing at its righthand varmature and back contact an energizing circuit for relay 89, as previously described` which locks up upon its energization. When sequence switch 900 arrives in position 10-1/8` a circuit is again completed from grounded battery, contact 913. conductor 98, contact 503, conductor y75, to

ground, through the windinof of relay 7 7, to cause the energization of this relay. Relay 77 is energized and causes the energization of relay 96, as previously described. When sequence switch 900 leaves position 10-1/8, relay 77 is denergized and causes the energization of relay 97.

When sequence switch 900 arrives in p0- sition 10-8/4 and until it leaves position 12, current` is supplied to the upper trunk conductor 7 3 from positive pole of battery, contact 914, conductor 99, contact 504:, conductor 82, to ground through the winding of polarized relay 86 and relay 87; Since this impulse is from the positive pole of battery, polarized relay 86 is energized in this circuit, relay 87 also being energized. A cilcuit is then completed from grounded battery, winding of relay 79, lamp 8, outermost left-hand armature and front contact of relay 97, outermost left-hand armature and front contact of relay 96, outermost lefthand armature and front contact of relay 89, outermost left-hand armature and front contact of relay 78, armature and front contact ot' relay 86, right-hand armature and front contact of relay 87, to ground. The lamp 8 is lighted in this circuit to indicate that the hundreds digit of the wanted line is8. Relay 79 is energized `in the same circuit, breaks one branch of the locking circuits of relays 78, 89, 96 and 97 and these relays are restored as before when relay 87 denergizes. When sequence switch 900 leaves position 12, relays 86 and 87 are denergized, the denergization of relay 87 causing in turn the denergization of relay 79. It is to be observed that in lighting the lamp 8, the same code of impulses was sent over the lower trunk conductor as was used in selecting lamp 9, but in this ease the impulse over the upper trunk conductor was of a polarity to energize relay 86, whereas, in lighting lamp 9, relay 86 was not energized. It will thus be seen that the polarity of thel impulse over the upper conductor and the resultant energized or non-energized condition of relay 86 determines which one of two lamps shall be lighted after the controlling relays 78, 89, 96 and 97 have been actuated by impulses over the lower trunk conductor.

When the sequence switch 900 arrives in position 12-5/8, an impulse will be sent over the lower trunk conductor from grounded battery, contact 914:', conductor 601, contact 602. conductor 75, to ground through the winding of relay 77. Relay 77 is energized and causes the energization of relay 78. When sequence switch 900 leaves position 12-5/8, relay 77 is denergized, causing the energization of relay 89, as previously described. When sequence switch 900 arrives in position 13-1/4- and until it leaves position 15, relay 77 is maintained energized over the circuit previously described,

causing the energization of relay 96. Since, in this`case, as will presently be seen relay 77 remains energized until the li htlng of the digit indicating lamp, relay 9 will not be' energized. Then sequence switch 900 arrives in position 18-3/4 and until it leaves position 15, current will be supplied to the upper trunk conductor 78 from the negative pole of battery, contact 915, conductor 603, contact 6011, conductor 82, to ground through the windings of relays 86 and 87. Since this impulse isV from the negative pole of battery, relay 86 will not be energized in this circuit. Relay 87, however, is energized and completes a circuit from grounded battery, winding of relay 79, lamp 7, right-hand armature and back contact of relay 97, outer righthand armature and front Contact of relay 96, outer right-hand armature and front contact of relay 89, outer right-hand armature and front contact of relay 78, ar mature and back contact of relay 86, righthand armature and front contact of relay 87, to ground. Lamp 7 is lighted in this circuit and relay 79 is energized to cause the release of relays 78, 89 and 96. When sequence switch 900 leaves position 15, relays 87 and 77 are denergized, leaving the relay combination in condition for reoperation.

When sequence switch 900 arrives in position 155/8 a circuit is completed from grounded battery, contact 916, conductor 701, contact 702, conductor 75 to ground, through the winding of relay 77. Relay 77 is energized and causes the energization of relay 78. When sequence switch 900 leaves position 15-5/ 8,relay 77 is denergized and causes the energization of relay 89. When sequence switch 900 arrives in position 16-1-/4 and until it leaves position 18, relay 77 is maintained energized over the path previously described, and, upon its energization, causes the energization of relay 96. Since, as in the selection of lamp 7, the relay 77 remains energized until the completion of the indicating operation, relay97 will not be energized When sequence switch 900 arrives in pcsiti'on 16-3//1 and until it leaves position 18, current vis supplied to the upper trunk conductor from the positive pole of battery, contact 917, conductor 7 03, contact 7 011,c0nductor 82,` to ground through the windings of relays 86 and'87. Since Athis impulse is from the positive pole of'battery, both the relays 86 `and 87 are energized. The energization of relays 86and 87 completes a circuit from -grounded battery, winding of relay 79, lamp 6, outer left-hand armature and back contact of relay 97, outer left-hand armature and front contact of relay 96, outer left-hand armature and frontcontact of relay 89, outer left-hand armature and front contactfoil relay 78, front Contact and armature of relay'86, front Contact and armature of relay 87, to ground. Lamp 6 is .lighted in this circuit to indicate that the units digit of the desired line is 6. Relay 79 is energized to break the locking circuit of relays 78, 89 and 96. When sequence switch 900 leaves position 18 relays 77, 86 and 87 are denergized, and the relays are in condition for reoperation. Y

The operator has now been informed by the successive lighting of lamps W, 9, 8,7 and 6 that the desired substation is party W on line 9876. The setting up of any desired number may be traced in the above manner by determining the character of the impulses sent and noting which relays are actuated in the successive sending positions of sequence switch 900. 1n Fig. 5 is shown a table indicating the character of the impulses required to set up any desired number.

lVhen sequence switch 900 arrives in position 1, a circuit is completed from grounded battery, power magnet of sequence switch 100, contact 120, conductor 121, terminal 122, brush 128, contact217, contact 918, to ground, for moving this sequence switch out of position 11 and into position 16, which is the talking position.

lVhen sequence switch 100 leaves position 11, the locking circuit of relay 20 is broken at contact 105 and this relay de'e'nergizes, completing a circuit from grounded battery, power magnet of sequence switch 200, contact 218, left-hand armature and back contact of relay 20 to ground, for moving this sequence switch out `of position 8 and into position 18. Y

lith sequence switch 200 in position 18, a circuit is completed from grounded battery, winding of down-drive magnet 124, contact 219, to ground. Magnet 124C is ener.- gized and causes the restoration of inder brush rod 21. lhen the cord linder is fully restored to its normal position, a circuit is completed from grounded battery, power magnet of sequence switch 200, contact 220, and a. contact 221, closed in the normal positionof the switch, to ground, for moving this sequence switch out of position 18 and into position 1. The cord finder and sender sequence switches are now in their normal positions and are ready for reuse.

When the operator at O has received the complete designation of the wanted line, she releases key K and inserts plug 125 into 'a jack 126 in which the wanted line terminates. Assuming that the called line is idle, a circuit is then completed for relay 71 from grounded battery, lampy 69, winding of relay 71, sleeve contacts of plug 125 and jack 126, andthe winding of c11t-oli-relay 127 to ground. Relays 71 and 127 are energized, relay 127 removing the control of the called subscribers line signal in the well-known manner. Relay 71 at its upper armature and front contact connects the upper talking conductor of the connecting cord to the test conductor of plug 125. At its lower armature and. front contact relay 71 completes a locking circuit for itself from grounded battery, shunting resistance 128, lower armature and front contact of relay 71, armature and front contact of relay 62, conductor 70, winding of relay 71, sleeve contacts of plug 125 and jack 126, and the winding of cut-ofi relay 127, to ground. The comparatively low resistance 128 shuntsI out lamp 69. Relay 62 is held energized at this time over a path from grounded batf tery, winding of relay 62, lower left-hand winding of repeating coil 63, contact 64 of key K, trunk conductor 65, terminal 66, brush 67, contact 129, lower right-hand winding of repeating coil 131 to ground.

After inserting plug 125: into jack 126 the operator depresses a ringing key (not shown) to supply ringing current of the desired character to ring the substation bell of the desired party.

When the called subscriber answers, a circuit is completed for supervisory relay 130 in the well-known manner. The operation of relay 130 completes a circuit for supervisory relay 132 over a circuit from grounded battery, upper right-hand winding of repeating coil 131, relay 132, contact 133, brush 83, terminal 84, trunk conductor 73, contact 134 of key K, and the upper lefthand winding of repeating coil 63, impedance coil 135, armature and front contact of relay 130, to ground. The connection is now complete and the subscribers may converse.

At the conclusion of the conversation, after the called party has replaced his receiver, the relay 130 will be denergized, causing in turn the denergization of supervisory relay 132. The hanging up of the calling partys receiver results in the deenergization of supervisory relay 136. The lighting of the well-known supervisory lamps (not shown) at the operators position indicated at O informs that operator that connection is no longer desired and she removes plug 14 from jack 15, whereupon relay 17 is denergized. The denergization of relay 17 completes a circuit from ground, armature and back contact of relay 17, contact 137, the winding of the power magnet of sequence switch 100, to grounded battery.

for moving this sequence switch out of position 16 and into position 18.

In position 18 of sequence switch 100, a circuit is completed from grounded battery, winding of down-drive magnet 138, contact 139, to ground. The brush set 58 is returned to normal position under the control of a constantly rotating roller 146. When brush 141 engages segment 142, at which time the switch will be fully restored, a circuit is completed from grounded battery, power magnet of sequence switch 100, contact 143, conductor 144, segment 142, brush 141 to ground, for moving this sequence switch out of position 18 and into position 1.

As soon as brush set 58 moved down from the terminals of the trunk over which the connection was established, the circuit of relay 62 is broken and the shunt circuit about lamp 69 is removed. The resultant lighting of lamp 69 informs the operator at O that connection is no longer desired and she removes plug 125 from the jack 126. The apparatus has now all been restored to normal and is ready for reoperation.

Referring now to that point of the opera'- tion in which the operator at O inserts plug 125 into jack 126, it will be noted that if the called line is busy, the operator will receive a click in the telephone set indicated at 145, due to the presence of potential on the sleeve conductor of iack 126. This potential will be supplied from grounded battery, either. through lamp 69 or through resistance 128, and when the tip of plug 125 engages the sleeve conductor of jack 126, a circuit will be completed from grounded battery, tip of plug 125, upper armature and back contact of relay 71, primary winding of coil 146, to ground, thus causing a click in the operators head-set to notify her that the desired line is busy.

What is claimed is 1. In a multi-office telephone exchange system, calling and called lines, a final connecting operators position, a trunk line, means including said trunk line for extending a calling line to said position, means for automatically indicating the number of the called line at said position, a combination oi*l relays to control said indicating means, and means to successively actuate said relay combination to cause the indication of the various digits of the number of the called line.

2. In a multi-oiice telephone exchange system, calling and called lines, an A. operators position, a B operators position, a trunk line, means including said trunk line to extend a calling line from said A operators position to said B operators position, means for automatically indicating the number of the called line at said B operators position` a combination of relays to control said indicating means, and means to successively actuate said relay combination to cause the indication of the various digits of the number of the called line.

3. In a multi-oflice telephone exchange system, calling and called lines, a final connecting operators position, a trunk line, means including said trunk line for extending a calling line to said position, means to send impulses of varying characteristics over said trunk line, means for indicating the number of the called line at said position, a combination of relays to control said indicating means and responsive to said impulses, and means to successively actuate said relay combination to cause the indication of the various digits oi the number of the called line.

si. In a multi-ofhce telephone exchange system, calling and called lines, a final connecting operators position, a vtrunk line, means including said trunk line for extending a calling line to said position, an impulse sending device, means to operate said impulse sending device to send impulses of varying characteristics over said trunk line, means for automatically indicating the number of the called line at said position, a combination of relays to control said indicating means and responsive to said impulses, and means to successively actuate said relay combination to cause the indication of the various digits of the number of the called line.

5. In a multi-oflice telephone exchange system, calling and called lines, a final connecting operators position., a trunk line, means including said trunk line for extending a calling line to said position, an impulse sending device, register switches, means to position said register switches, means to operate said impulse sending device in accordance with the positions of said registers to send impulses of' varying characteristics over said trunk line, means to automatically indicate the number of the called line at said position, a combination of relays to control said indicating means, and means to successively actuate said relay combination in accordance With the impulses sent to cause the indication of the various digits of the number of the called line.

6. In a multi-office telephone exchange system, calling and called lines, a final connecting operators position, a trunk line, means includingsaid trunk line for extending a calling line to said position, an impulse sending device, means to operate said impulse sending device to send sets of impulses of varying characteristics over said trunk line, means for automatically indicating the number of the called line at said position, a combination of' relays t0 cont-rol said indicating means and responsive to said impulses, and means to actuate said relay combination in response to each set of impulses to cause the indication of a digit of the number of the called line.

7. In a multi-oi'lice telephone exchange system, calling and called lines, an A operators position, a B operators position, a trunk line, means including said trunk line `for extending a calling line from said A operators position to said B operators position, an impulse sending device and register switches at said A operators position, means to position said register switches under the control of said A operator, means to operate said impulse sending device in accordance with the positions of said register switches to send sets of impulses of varying characteristics over said trunk line, the character of each set of impulses being determined by one of said register switches, means to automatically indicate the number of the called line at said B operators position, a combination of relays to control said indicating means, and means to actuate said relay combination in response to each set of impulses to cause the indication of a digit of the number of the called line.

8. In a multi-oifice telephone exchange tem, calling and called subscribers lines, a final connecting operators position, a trunk line, means including said trunk line to extend a calling line to said position, means for automatically indicating the number and party station of the called subscriber at said position, a combination of relays to control said indicating means, means to actuate said relay combination to indicate the party station designation of the called line, and means to successively actuate said relay combination to cause the indication of the various digits of the number of the called line.

9. In a multi-ofiice telephone exchange system, calling and called subscribers lines, a final connecting operators position, a trunk line, means including said trunk line to extend a calling line to said position, a plurality of number and party station indicating lamps at said position, a combination of relays to control said indicating lamps, means to actuate said relay combination to cause the indication of the party station designation of the called line, and means operative thereafter to successively actuate said relay combination to cause the indication of the various digits of the number of the called line.

l0. In a multi-ofiice telephone 'exchange system, calling and called subscribers lines, a final connecting operators position, a trunk line, means including said trunk line to extend a calling line to said position, means to send sets of impulses over said trunk line, a plurality of number and party station indi-` cating lamps at said position, a combination of relays to control said indicating lamps, means to actuate said relay combination in accordance With a set of impulses llO to indicate the party station designation of the called line, controlling relays, means operative after the indication of the party station designation to successively actuate said relay combination to cause the indication of the various digits of the number of the called line in response to successive sets of impulses, and means to energize said controlling relays after the indication of the party station designa-tion to remove the control of saidparty station indicating lamps from said relay combination.

l1. In a multi-oce telephone exchange system, calling and called lines, a nal connecting operators position, a trunk line, means including said trunk line to extend a calling line to said position, a plurality of indicating lamps divided into two groups,

a combination of relays to determine which lamp of 'a roup shall be lighted, and a 10 polarized re ay to determine in which one of said groups a lamp shall be lighted.

In Witness whereof, I hereunto subscribe my name this 6th day of April, A. D. 1917.

EDGAR H. CLARK.

Copies ot this patent may be obtained for ve cents each, by addressing the Commissioner ot Patents, Wallington, D. 0." 

